Apparatus for stripping bark from step-by-step advanced sawmill edgings or slabs



J. R. ROBERTS APPARATUS FOR STRIPPING BARK FROM S Dec. 27, 1949 TEP-BY-STEP ADVANCED S AWMILL EDG ING S OR SLABS 4 Sheets-Sheet l Filed Sept. 18, 1947 Dec. 2 7, 1949 Filed Sept. 18, 1947 J. R. ROBERTS APPARATUS FOR STRIPPING BARK FROM STEP-BY-STEP ADVANCED SAWMILL-EDGINGS OR SLABS 4 Sheets-Sheet 2 Dec. 27, 1949 1. R. ROBERTS 2,492,321

APPARATUS FOR STRIPPING BARK FROM STEP-BY-STEP ADVANCED SAWMLL-EDGINGS OR SLABS 4 Sheets-Sheet 5 Filed Sept. 18, 1947 I nyen tor John R. Rober/s Dec. 27, 194i;m

J. R. RoBRTs APPARATUS FOR STRIPPING BARK FR 0M STEP-BY-STEP ADVANCED SAWMILL-EDGINGS OR SLABS 4 Sheets-Sheet 4 Filed Sept. 18, 1947 Inventor N e n R R. n m J QS Q Q QQ Q m n Mw n .wm QQ .mm

Patented Dec. 27, 1949 APPARATUS FOR STRIPPING BARK FROM STEP-BY-STEP ADVANCED SAWMILL EDG- INGS R SLABS John R. Roberts, De Valls Bluir", Ark.

Application September 18, 1947, Serial No. 774,700

14 claims. l

This invention relates to machines for removing the bark from slabs, edgings and the like which have been sawed off from logs in sawmills and it has for its principal purpose to produce a simple and sturdy automatically operating apparatus which performs the desired operation reliably to such an extent that the resulting product may be used for the making of Wood pulp.

It is one of the principal objects of the invention to provide an apparatus of this type, which obtains the desired result by advancing the slab to be freed from the bark toward chisels, knives or teeth performing this operation in a step by step advance, each step resulting in an advance over a limited distance.

Itis a further object of the invention to provide simple means for the automatic advance of the slabs in steps such means including gripping means adapting themselves automatically to the shape or configuration of the slab.

It is a further object of the invention to provide means for automatically applying and removing the debarking chisels, knives or teeth when the slab moves into the proper position.

It is a further object of the invention to control these automatic means, by a movable member actuated by the slab itself during its advance.

It is a further object of the invention to automatically remove the debarking chisels, knives or teeth from the slabs when they get stuck so that the slab carries them with it or is stopped by them.

Further objects will be apparent from the following detailed specification.

The invention is illustrated in the accompanying drawing showing one embodiment thereof by way of example. This example will illustrate the constructive principle and also one mode of application of the machine, but it does not illustrate modifications of the constructive details many of which, once the principle and the problem to be solved have been explained, will be more or less within the range of the skill of the expert. Modifications of the inventions are therefore not necessarily departures from the essence of the invention.

In the accompanying drawings:

Figure 1 is a plan view of the machine.

Figure 2 is an elevational side view of the machine.

Figure 3 is an elevational sectional view, the section being taken along the plane of symmetry.

Figures 4 and 5 are sectional elevational end views the sections being taken along lines 4-4 and 5-5 of Figure 1, respectively.

Figure 6 is an elevational sectional view of a detail.

Figure 7 is a sectional plan view of a detail.

Figure 8 is an elevational view of a detail.

Figure 9 and Figure 10 are perspective views of details.

In sawmills it is customary to remove bark carrying slabs and edgings from logs. The slabs have usually approximately the shape of a cylinder segment, with the round surface carrying the bark. As the slab has been cut away from the outer surface of the log it consists essentially of valuable pulp material, and is even of special value for the making of cellulose as it is the portion richest in sap. It will therefore be clear that repeated attempts have been made to make this material available for the wood pulp manufacturer by removing the bark which is not usable.

The principal purpose of the invention thereforeconsists in providing a debarking machine whichy is specially adapted for slab debarking Work.

The slab debarker according to the invention comprises a frame I I on which all the parts and mechanisms are mounted.

It carries xedly mounted slab clamping means I2 and guide rails I3 ior a reciprocating carriage I4 which carries a reciprocating feeding mechanism. It moreover carries the debarking mechanism generally indicated at 5I) and described below.

The fixed-slab clamping and holding mechanism consists of a plurality of teeth holding supports I5, one of said supports being arranged near the admission end ofthe frame. Each support I5 is U-shaped and has a bottom piece I6 on which the slab rests and two lateral upstanding shields II. On these shields a frame I8 is mounted carrying a cross bar I9.

The shields hold an axle 2I serving as a pivot or fulcrum for a row of clamping teeth 20 which may turn around said axle and are therefore provided with bores.' A large number of clamping teeth 2Il are arranged side by side, each of which is individually-movable. Each clamping tooth is provided with an eye 22 at its upper end, which holds the end of a coiled spring 23 the other end of which is held in a hook carried by the cross bar I9 of the frame I8. Therefore each clamping tooth is individually under spring tension and is pressed with its free end against the bottom on which the slab rests. The clamping teeth at their downwardly directed ends 24 are preferably pointed and provided with cutting edges which engage the bark covered surface of the slab and which are adapted to hold it rmly.

, side on the axle, each tooth having In front cf the iixed slab clamping mechanism at the admission end a number of rollers 25 (Figure l) are arranged (one being merely shown in the drawing) over which the slab is moved when it enters the U-shaped support I5 with its at face resting on the bottom. Near the point where the slab enters two strong resilient curved guides 2S are mounted, which engage the sidesof the slabs and guide it towards the central .or middle portion of the clamping and feeding mechanism. The resilient guides 26 are adjustable and may turn around pivots `21. They are prD- vided with ears 28 engaged "by strong coiled springs 29 pressing them inwardlytowards the middle zone.

The guide rails I3 are longitudinally disposed along the frame I I and they form a slideway for the carriage I4 of the 'reciprocating feeding mechanism 34. This mechanism consists of a plurality of U-shaped supports 35, similar to the supports I5 .of the ixed clamping mechanism, but' mounted onthe carriage I4, each consisting of a bottom piece .31 yo 'n which the flat surface of the slab may rest andfof two shields 3 8. .The latter carry an axle 39 forming a -fulcrum for the feeding teeth 40. A row consisting of a large number of such feeding teeth is mounted side by a bore through which the axle passes. The feeding teeth are therefore individually movable and may loccupy ,different positions so `vas toladapt .themselves to the shape of the-slab. Each tooth 40 is provided with an eye 4I at its upper end. T-he support 35 moreover carries a frame 36 provided with across bar 42. A row f coiled springs 44 is inserted .between the eyes 4I of each-:tQoth-d .and hooks projecting from the cross bar 42 The coiled springs :draw vthe ends-45 .of teeth 4 0 towards the work piece resting .on the bottom piece 31. v-The slabs are thus irmly gripped. It`v will b e noted .that the clamping teeth are held `in an inclined position and that they have pointed cutting edges 45 :adapted to penetrate into and to `thereby firmly engage the bark covered upper .surfaceof the slab resting on the bottom pieces 31.

The carriage I4 is provided with guide sleeves `46 which slide von the `guide rails VI3, In the example shown the rails are cylindrical `rods which are completely encircled by the sleeves.

Each carriage, .as has been mentioned, is provided with a plurality of supports 35 carrying feeding teeth, two such supports fbeing she-whim the example illustrated.

The reciprocating movement of the carriage is produced by a driving mechanism comprising a dri-ving pulley t@ mounted on the rear end jof the frame II on a shaft 6I. This drivingpulley is driven by a belt or cable QI? :infany other appropriate manner (not shown) from'ia motcr lof any type.

The shaft 6I is journaled in bea-ringsi and carries Aa pulley 63 drivin-g, by vmeans ofl a 'belt transmission 52, the pulley 64 Aon shaft 65. 'A roller 66 is provided for tensioning the belt; `this roller may be adjustable for instance by mounting it on rockable arms. Shaft A(i-carries the'two driving disks 61 arranged on each side, each provided with a driving pin-BB actuating a pitman rod 69 which is pivoted tok a link 10 fulcrunid at 1I on a pivot carried by thejcarriageframe I I. The other end of the link carries a 'further link 12 pivoted at 13 to the carriage. By virtue of the double disk driving arrangement the carriage is thus operated on both sides by the links 10,12.

The debarking mechanism generally indicated at 50 is carried by uprights 15 projecting upwardly from a U-shaped support 'I6 which is provided with guiding sleeves 11 slidable on the guide rails I3. The support 16 may be integrated with the U-shaped support 16 of one of the xed slab clamping devices I2' which in this case is also provided with guiding sleeves 11 Sliding on rail 13 (Figure 3). In this Acase the two supports 16 and 16' form a single U-shaped unit.

The uprights 'I5 are pivoted on the supports 16 by means of pivots 19. Their position together with the position of the parts carried by them is adjusted by a pitch adjustment device which consists of a rod BI pivoted to the uprights and Ypassing through a bore in a laterally projecting ear 8,2. The rod is threaded and either may engage threads in the bore of the ear or may pass freely through said bore and be provided with nuts 82 on both sides of the ear permitting adjustment of the `eiective length of therodwhich is that portion of the rod located between kthe -ear andthe. point at which it is pivoted to .thesupright ,15, It will be clear that in this way the inclination of the upright towards the vertical may vbe finely adjusted.

.The uprights 15 are provided with lslots.1lll2e=fn1f a purpose mentionedbelow and are joined bya transverse vbar 83 and by transverse holding plates 84, 84, 85 which `are sodisposedtha-tf they enclose and hold between them the entirefselies or row of debarkingfchisels .or teeth S0. These debarking teeth or chisels `are shown separately in Figure 10. They are of .a rectangular or square cross section and are providedwith` slots .9L At their ends 92j they Vare pointedandbutting edges 93 are formed which :are applied against the bark covered surface of the l:sla-b.. Each V tooth or chisel 9B is moreover provided with an eye `94 into lwhich a coiled vspring maybe hooked. v

The teeth are aligned between the two .nprights 15 on one hand and betweenthe yholding plates 34, 84 and 85 on the vother hand. iTheyare in 4frictional contact with each other and are freely movable Vin an axial direction, f but.-.ar.e otherwise guided laterally by means vof thenprights and holding plates. The uprightsguide I nerely the two outer members of the series,y .but on :account of the alignment of the rteethand because :the space between .the uprights yisillled completely and snugly they act as each others guiding surfaces, if moved separately. When the teeth are aligned between the uprightsthesslots 9 I .are ,also aligned.

On the outside the uprights 15 on bothsides carry supporting shields 95 joined .to themloy bolts with jam nuts in order to be able toremove the structure carried by the shields for repairs, In the example shown, the Supporting shields'are arranged at a small distance from the uprights so that the heads of the pitch adjustment rod, the vertical portions .of the U-shaped supportsl and other parts may be arranged between them. Each supporting shield carriestwo opposed hy.- draulic or air cylinders t6, 91 provided with pistons 98 (visible in Figure 6 only) which are joined by a common piston rod99 The .pistons are positively operable on either strokeby the pressure fluid admitted into one of the cylinders. The two piston rods 99 on the sides of the ydebarking mechanism are joined by a yoke -b'ar i @d .which passes through slots v(II in the shields, through the slots .I 02 in the uprights 15, alreadymengA tioned above, which are aligned with the slots IV-QI -and through the slots 9| of the debarking chisels `orknives 90. At each end the yoke bar is provided with a head |03 xed to the piston rods 99, and with a projecting wing or bracket |04. Moreover a frame |06 of U-shape depending from the heads and arranged in substantial parallelism with the row of chisels or debarkng knives 90 at a small distance behind the same is xed to said heads by means of lugs |65, projecting rearwardly from said heads.

Y The transverse or cross bar member of the U-shaped frame |06 serves as a support for a series of coiled springs 2I0. Each of said springs is allotted to one of the debarking chisels or knives 90V and is attached to said cross bar of the frame on one hand yand to the eye 94 on the other hand. It will thus be seen that if pressure uid is admitted to one cylinder, while the other cylinder is connected with the exhaust, the piston rod 99, the yoke bar |00 and the frame |06 with all the springs are forced down, the relative position of these parts remaining unchanged.

The wing bracket |04 carries a chain or cable holder |01 to which a cable |08 is attached. The cable is wound on a drum |09 which is Xed on a shaft I I0 carried in journal brackets I I I. Further drums I I2 are keyed on said shaft and cables I I4 are wound and attached to them. These cables are attached on their other ends to coiled springs which are secured to the upper xed holding plate 84. This plate may preferably be formed by an angle, on the projecting flange of which the ends of the coiled springs are fastened. It will therefore be understood that when the piston and yoke bar move down the springs l I5 are tensioned and return the piston rod and yoke bar as soon as the pressure of the pressure fluid on the upper piston drops.

Thel two cylinders 96, 91 are operated by a pressure fluid such as air or a hydraulic fluid according to circumstances.

Assuming the pressure iiuid to be air, suitable air lines |20, I2I connect the two cylinders on both sides respectively and the line |20 connecting cylinders 96 of both sides is supplied by air line |22 leading to control valve |25 on one side while connecting line |2I for the two cylinders 91 is supplied by line |23 leading from the control valve |30 on the other side. Both valves are supplied by a common bifurcated supply line |28.

` Thev control valves themselves are of the customary type, for instance of the type provided with a piston establishing communication between bores or channels in communication with the cylinder controlled by the valve and the admission line and discharge line or opening (not shown) respectively and only the outside of the valves is shown. They are controlled by a piston valve rod |26, |21 respectively, each being under the tension of a spring |29, |39 respectively. The piston valve rod |26 is provided with a forked head |32 through which a trip bar |33 passes.

The automatic control of the valve is effected by means of a slab operated trip plate |40 which is mounted on an axle |4| held within the frame II and which projects upwardly through a slot |42 in the bottom part 18 of the U-shaped support 16 below the debarking chisels or knives. The trip plate is preferably weighed by means of weight |43. Under the influence of the weight it adopts an inclined position as shown in Figure 3 with its upper edge above the support 16 so that a slab sliding into position on the support will depress said upper end and will turn the plate |40 and theaxlelM. f

The trip bar |33 is xedly attached to that part of the axle |4I which projects outwardly through the frame I I. It will therefore be clear that when a slab being pushed along the support, reaches the position below the debarking chisels, it depresses the tripping plate and thereby turns the plate with its axlev and with the tripping bar |33 attached to it. The tripping bar pushes back the forked head |32 of the valve piston rod |26 and opens the valve so that air is admitted to piston 96 t0 force the debarking knives down on the slab. After the slab passes the tripping plate |40, valve |25 is closed by spring |29, air pressure on piston 96 ceases so that springs I|5 unwind cables, I I4 and rotate shaft I I0 to wind up cables |08-, which raise yoke bar |00 and thus lift the chisels out of the path of an oncoming slab It has already been described that the support 16 carrying the uprights 15 and the debarking mechanism is movable on the rails I3 by means of the sleeves 11, such movement being independent of the reciprocating carriage movement produced by the drive pulleys. This movement is permitted because the chisels or knives might dig into the slab in such a manner occasionally that they cannot detach themselves, but get stuck.

In this case the slab advanced by the'carriage movement would move the entire support 16 with its machinery on the rail I3. This movement is limited and is moreover utilized for detaching the chisels from the slabs. The slidable support 16 is provided with projecting brackets |44 entering into suitable heads |45 of draw bars |46 passing through bores in spring retainers |48. Between said spring retainers and the end of the draw bars |46 provided with suitable spring pressing disks, strong springs |41 are inserted, which provide a suitable resistance against shifting of the unit 50 on the rails I3.

Moreover the head |45 located in front of valve |30 also acts as an actuator or control member for said valve. When the unit is moved by the slab it strikes against the end |49 of piston valve rod |21 and thereby actuates the piston in valve |30 so that air is admitted to the cylinders 91 through pipes |23 @and |2I. The pistons 91 will push the piston rods 99 upwardly and will therefore disengage the debarking chisels from the slabs. The springs |41 then pull the unit 50 back, and the piston of the valve |30 is returned by spring |39, thus permitting the pressure uid to escape.

The slab debarking operation has partly a1- ready been described and may be summarized as follows.

The slabs or edgings are pushed in over the` rollers 25 and are held in a middle position by the resilient guides 26. They advance pushing the teeth 20 of the Xed clamping device I2 upwardly. These teeth are inclined and rest on the bark of the slab, along its entire contour, whatever the shape of Icontour as the teeth are individually movable and will adjust themselves to this contour which is normally approximately `a part of a cylinder. The slab advances further and comes under the teeth 40 of the reciprocating feeding mechanism 34 driven by the pulleys and finally under the debarking mechanism 50. Considering now merely the automatic'operation the tripping plate |40 is turned when the slab reaches the position below the chisels 90 and the valve |25 is operated. This lowers the debarking chisels, as air is admitted to cylinders 96, thus lowering the yoke bar |00 and the row of chisels. As each chisel or knife is held by its own coil spring ||0 the chisels or knives adjust ythemselves perfectly tothe contour .ofthe slab.

iii/@oefenver,y .the angle. between :the chisels ari-clothe slab may be .zadrusted :by-means of the `pitch adiiustment bars.

The: ,carriage i4 L is meanwhile 1 reciprocatedv by means-.of pnlleysf `.and lidzzand-ipitmanwrods 159, driven by` disks 61 andby means Aof linksli and J2- Buring .theiorward movement ofthe carriage the slab advances v.vvil'ih `the `carriageins/ith'thel chselsfslicing .oiwthe .abarkrom the slab-.during this.. stroke.. During the return movement .of the :carriage .the fixed :clamping devices d 2 by means of their :teeth .movable .around f .axle 2i f-prevent any .backward movement `ofthe slab, :as the teeth im `account of their inclined positionandipointf ed :putti-.11g .edges g penetrate deeper and ldeeper into the slab if such movement is. attempted. The carriage therefore moves back while :the slab remains. stationary butA car-ries the slab forward again Withl the4 next stroke, `.the ,teeth f 4D holding the.. .fslabiiirmly on 1 the carriage duringrtliis. fory Welfdf movement. =.Again'.the .chisels slice oi the barkfandthe operation :is repeated.

'The opera-tien `vvlfnen the chisels get :stuckin tlsiev slaby has alreadytbeen- :des cribed.

'Lit istbei'efore ,seenzthatthe bark-is removed hyattv seriesroffshorttimed step by stepzadvance movements `with 'pauses 1 :between them. It has been r found by `experience that this .method .is thecestmode of removing .between ;85% to 100% of `the barkyofthe slabs, .As a removal Yof .80 0f the barkiwillmake the :slabs :iit'for the Amaking of wood pulp, 4:the product of the machine will practieallyfrbe fully utilizable.

@It will vvbe :understood vthat Yfthe vnumber v`of clamping :andugripning rdevices fused in .the -ma- Chine-@depends largely von circumstances .and .on the' nature; .and presence .of :auxiliary appliances for feeding removal.` rand other operations. YThe number show-n ris necessary. in casesY .in A.which the slab-is vSupposedrtogbe;fed .by'hand or by auxiliary appliances to ,acertainrpoint in front of the `debarking structure and to be :delivered at ...another pointe-inthe rear ofthedebarker., `the machinev takin-gncare-of -the--movementibetween thesel two points. Manifestly the last reciprocating grips ping device-defines the -last` mentioned point. rIn other respects ythenumber-Yand distribution o1 the; clamping and gripping devices is Vsubject to change 4.according Lto ycircumstances..

The inventionglms been described by giving specific :examples-:oi Vthe @details zused. hasxto be emphasized however that thevspeciec Idesigns of the details mentioned in the foregoingfspeciligation :are not.- connected .with :the invention in;` such `wav' that a change inthe details-will i ,Y enarture from what is consideradas the inventen- Havingziiescribed the invention, what :is claimed as new-is:

lilla-slab debarking--smachine, ia-"fiame, a series :offindependent debarking .chisels eachv capableiof beingpressedr against Vthefs'lab independentlyrof' thecther and arranged in aseries disposed 4transversely Aiv-nih respect .tofthe slab, means Ioradvancing the slab-step by step .toward the debarlsing--chisels, saidsmeanscomprising ,a repliestrig V.Slabfcai-living ."carriage, slab grip.-` ping devices fmountedpon said carriage and comprisingaseries .of Ain.dividually movable inclined teeth, separate -means for pressing; each .of said teeth-.against the slabior holding said :slab lon saidarriage and for grasping. .said slab when .he y,carriage eadyances toward the idebark'ing cbisels, while-releasing theslab during the ateturn movement of the carriage, elampingdevics 'Xed -on'the frame, each comprising a number of individually movable inclined teeth, meansror pressing -the teeth separately Vagainst ythe slab,I 'for clamping ,sa-id slab and Y holding it dii-ringV thereturn movement Vof said carriage.

'2. In a slab debarking machine, af-rame, a series off independent/debark-ing chisels yeach `capable -oi being pressed against theslab independently of the other and arranged ina seriesdisposed transversely with respect to the slab, means for advancing the slab step -by stepftoward the v`debarking chisels, said Vmeans comprising avreciprocating slab carrying carriage, vguiding"rails along said Yframe, vguiding sleeves on said y'carriage. slidable Yon `sia-id rail, driving` means lforse/id carriage vfor .producinga reciprocating movement, slab gripping devices mounted on said vcarriage and `comprising `a seriesl of 2 individually :mov-able inclined teeth, separate meansrtor pressing each Aof .said teeth against 4the slabifor holding-:said slab on said carriage .and for grippingy said when .the .carriage .advances .toward the vdebar'king chisels, while-releasing ,the slabJduring the return movement. of .said carriage, vclamping 'devices 'xed on .the -:frame,..ea.c`h comprising a num.` ber of individually movable inclined teeth, means for `pressingthe teethseparately against the slab, for-clamping said slab. vand holding it during the return movementV ofA :said carriage.

3. Ina slabpdebarking machine,:,aframe,=means for advancing the. .slab .step A`by step, vsaid i:neaisis comprising ,a reCiprOQatiDgsIab .carrying carriagesl ab gripping devices .en .said carriage ,each including individually mov-able inclined teeth, separate means V-for pressing ,each .of isaidteeth against the .slab .for gripping and holding the latter on the carriage during the advance. ofthe carriage, While releasing saidfgrippingaction :during the return movement; further gripping :and clamping devices fixed on saidirame,.:each inf eludilg .a :number v.-of individually movable-nelined teeth; means 'forxpressing the same. against the slab for holding the .slab Alering-.theret-.urn move-merit of. .the carriage, .a series ofdebarking ehsels :eilig-.neel` in vtra-.nsverse-irovv with respect to the A .direction -ofadvanceof thesiab, smeans for holding Saxidseriesso-alignedfdebarking chisels above :said .slabfmeansior :moving-.the .entire series .of -debarkingscliisels -toWardif-:theizslab fand.- away from the sa11r1e.,andY separatefsneans for pressing @ath individuel `chisel' toward theslab when zthe series hasfbeen. mOYQd -intocontact with the same.

4. .In av slabfdebarkingfmachine, .a framefmeans lfor advancing theslab step Aby step, 4said-nieaigls comprising a reeiprotatingslab Carrying carriage.

slab gripping devices on` said -carriagefeaoh ,in -V cluding individually ,movable .inclined teeth, sep. arate .means f or .pressingweach of. said teetl'i aga-inst the slab -forgripping and .holding the flatter on .the carriagev during theadvaneefofithe Carriage-While releasing Said. gripping. action Yiuring the Areturn movement, furthergripping .and clamping .devices jxed on said frames. Cach i11- cludingl a number -of individually movable inf. clined teeth,- means for pressing the samefag-ainst theksla'b for holding the Slab during..the'1'etn13-u' movement .of the carriagaan upstanding chisel' supporting structure mounted ,on saidaforesaid frame, includingl lateral and transverseguiding members forming a guiding, framework, a: series of debarking chisels aligned andmovable within said guiding yfra-mework and movable as aseries toward and away from said slab, separate means 9 for pressing each debarking chisel downwardly into the lowermost position within the series and into contact with the slab, and iiuid pressure operated means for moving, the series of chisels downwardly toward the slab and upwardly away from the slab.

5. In a slab debarking machine, a frame, means for advancing the slab step by step, said means comprising a reciprocating slab carrying carriage, slab gripping devices on said carriage each including individually movable inclined teeth, separate means for pressing each of said teeth against the slab for gripping and holding the latter on the carriage during the advance of the carriage, while releasing said gripping action during the return movement, further gripping and clamping devices fixed on said frame, each including a number of individually movable inclined teeth, means for pressing the same against the slab for holding the slab during the return movement of the carriage, an upstanding debarking chisel support, mounted on said aforesaid frame, provided With lateral uprights and transverse members forming a guiding frame, a series of debarking chisels aligned and movable within said guiding frame and movable as a series toward and away from said slab, separate means on said guide frame for pressing each debarking chisel toward a slab when brought into operative position on the same, pairs of opposing cylinders, each pair of cylinders being joined by a common piston rod operated alternatively by fluid pressure within the cylinders, a transverse member connected to said common piston rod for producing the joint upward and downward movement of the series of chisels and means for supplying the cylinders alternatively with a pressure uid.

6. In a slab debarking machine, a frame, means for advancing the slab step by step, said means comprising a reciprocating slab carrying carriage, slab gripping devices on said carriage each including individually movable inclined teeth, separate means for pressing each of said vteeth against the slab for gripping and holding the latter on the carriage during the advance of the carriage, while releasing said gripping action during .the return movement, further gripping and clamping devices xed on said frame, each including a number of individually movable inclined teeth, means for pressing the sameV against the slab for holding the slab during the return movement of the carriage, an upstanding chisel supporting structure pivotally mounted on said frame, and provided with lateral uprights and transverse members forming a guiding framework, means for adjusting the angular position of said chisel supporting structure with respect to the direction of advance of the slab, a series of debarking chisels aligned and movable within said guiding framework and movable as a series toward and away from said slab, separate means for pressing each debarking chisel downwardly into the lowermost position within the series and into contact with the slab, and fluid pressure operated means for moving the series of chisels downwardly toward the slab and upwardly away from the slab.

'7. In a slab debarking machine, a frame, means for advancing the slab step by step, said means comprising a reciprocating slab carrying carriage, slab gripping devices on said carriage each including individually movable inclined teeth, separate means for pressing each of said teeth against the slab for gripping and holding the latter on the carriage during the advance oi the carriage, While 10 releasing said gripping action during the return movement, further gripping and clamping devices fixed on said frame, each including a number of individually movable inclined teeth, means for pressing the same against the slab for holding the slab during the return movement of the carriage, an upstanding debarking chisel supporting structure mounted on the aforesaid frame and provided with lateral uprights and transverse members forming a guiding frame, said lateral uprights being provided with slots, a series of aligned debarking chisels each provided with a slot and each movable within said guiding frame, individual means associated with and carried by said guiding frame for keeping each member of the series under pressure, cylinders mounted on said chisel supporting structure and containing fluid under pressure for operating piston rods, a transverse yoke member secured to said piston rods and passing through the slots oi the uprights and of the chisels to move the entire series, and resilient means associated with said guiding frame and tensioned when the entire series is moved in one direction. f

8. In a slab debarking machine, a frame, means for advancing the slab step by step, said means comprising a reciprocating slab carrying carriage, slab gripping devices on said carriage each including individually movable inclined teeth, separate means for pressing each of said teeth against the slab for gripping and holding the latter on the carriage during the advance of the carriage, while releasing said gripping action during the return movement, further gripping and clamping devices fixed on said frame, each including a number of individually movable inclined teeth, means for pressing the same against the slab for holding the slab during the return movement of the carriage, an upstanding chisel supporting structure movably and slidably mounted on said frame, said structure comprising lateral and transverse guidingk members and forming a guiding framework, a series of debarking chisels aligned and movable within said guiding framework and movable as a series toward and away from said slab, separate means for pressing each debarking chisel downwardly into the lowermost position Within the `series and into contact with the slab, and fluid pressure operated means for moving the series of chisels downwardly toward the slab and upwardly away from the slab.

9. In a slab debarking machine, a frame, means for advancing the slab step by step, said means comprising a reciprocating slab carrying carriage, slab gripping devices on said carriage each including individually movable inclined teeth, separate means for pressing each of said teeth against the slab for gripping and holding the latter on the carriage'during the advance of the carriage, while releasing said gripping action during the return movement, further gripping and clamping devices xed on said frame, each including a number of individually movable inclined teeth, means for pressing the same against the slab for holding the slab during the return movement of the carriage, guiding rails mounted on said frame, guiding sleeves on said carriage sliding on said rails, an upstanding chisel supporting structure having guides slidable on said guide rails, said guides mounting said chisel supporting structure for movement independent of said carriage, said chisel supporting structure including lateral and transverse guiding members forming a guiding framework, a series of debarking chisels aligned and movable within said guiding framework and movable as a series toward and away from said slab;y separate meansv for pressing'each debarkin'g eh" el downwardly intothe' lowermost position within the seriesandintoC conta-ct with' the slab, and fluid pressure operated means for moving the serieso-f chiselsv downwardly toward the' slab and upwardly vaway from'th'e slab.

1U. In a slab debarking machine, a frame, means for advancing the slab step by step, said means-*comprising a reciprocating slab carrying carriage, slab gripping devices on said carriage each including" individually movable inclined teeth., separate means for pressing each of said teeth against the slab for gripping and'holding latter onv the carriage during the advance of the carriage, wliiley releasing saidgripping action during tire return movement, further gripping and'clampingdevices-fixed on said frame, each including a number ofindividually movable inclined' teethf,y means forpressing thesame vagainst the slab for holding the slab during the return AHiov'em'ent of the'l carriage, a chisel supporting structure mounted on saidff'rame, including lateral lain-d" transverse guiding` members forming a guiding framework, a series of debarkin-gr chisels aligned and movable within saidK` guiding framewoifkiandmovablelas-a series towards and away from-said'slab, fluidpressure operated means for moving theseriesf off aiigned chisels, valve means ier' controlli-ng the pressure Huid supply and f means-operated'by the slab for controlling said valvenreans.

Ll. a! slabf' deba'rkifng machine, a: frame, means for advancingtlfie slab step by step, said means comprising a* reciprocating slab'carrying carriageg. slab"v grippingdevices on sai'd carriage eaolr' includ-ing individually' movable inclined teeth; separate means'for' pressing each of said teethfagainst the: slab for gripping' and holding the'latter on the carriage during' the advance i of the carriage, whilerele'a'sing" said gripping action during: the return movement, further gripping and; clamping devices fixed'v on said frame, each'- including `a number of' individually movable inclined teeth, means for pressing the same against the slab for holding the slab `during the return movement o'f the carriage, a chisel supporting structure mounted on said frame, includinzg; lateral and transversev guiding members forming a guiding' framework, a'seresoi debarkingfchisels'aligned and' movable within said guiding framework movablev aslr aseries toward and awayv from said slab,- luid pressure operated cyl- 12. In a slab debarking machine, as claimed in claim" 9, and means to control the'uid pressure means that move the' series of chisels upwardly andafw'ay 'from the slab, said control meansbeing operated'by the slidable chisel supporting struc'- ture when the latter' slidesv independently along the guiding rail.

133. Ina slab debarking machine, as claimed in clam-1L 9, meansfor limiting the independent sliding movement of v'theclnisel supporting structure comprising lateral brackets projecting from said structurel through thev frame, and spring means fixed onthe irameattached to said brackets and opposing movement' of said structure in the slab advancingfdirection. y

Pi. In' a slab' debarking machine, a frame, means-for advancing the slabstep by step, said means comprising a reciprocating slab carrying carriage, slab gripping devices on'said carriage each including' individually movable inclined teeth, separate means'rfor pressing each of said teeth against't'he slabfor gripping and holding the` latter on-'the carriage'dfuring the advance of the carriage, while releasing said'gripping action during' the return movement, further gripping and clamping devices :liged onsaid frame, each inciudin'g a number ofr individually movable inclined teeth, means for pressing the same against the slab for holding the slab during the return movement of the carriage, a chisel supporting structure mounted' on said frame, including lateraland transverse guiding members forming' a gnidingframework, a series of debarking chisels aligned and movable within said guiding framework and' movable asfvseries towards" and away fromsaidslab, said chisel supporting structure beingsI-idable on' said frame, means for limiting saidfslidngfmovement of' the chisel supporting structure including brackets and springs attached thereto, cylinders containing fluid pressur'ef oper-"ated,` pistons for producing a downward movementro'fthe vseries ofl aligned chisels and iurther rcylinderscontaining fluid pressure operated pistons for" producing an upwardl movement of said'seri'esf; Valve means' for controlling the admissionl of pressure fluid to said cylinders, actuatingf means for said valve means, theactuating means tor the-valve controlling the upward movemerit of the seri'e's ofr chisels being engaged and operated byv the vbrackets'fwhen the chisel supporting structure slides relatively to the frame and approaches one limit of Vthe sliding'motion'.

JOHN R. ROBERTS.

REFERENCES CITED The" following references are ofv record in the ille of this patent:

UNITED STATES' PA'IENTS Nui-'naher Name Date 467,899 Reed Jan. 26, 1892 1,589,603 Saprones May 26, 1925 

